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Abstract:

A yaw rate sensor having a substrate which has a main plane of extension,
and a Coriolis element is proposed. The Coriolis element is excitable to
a vibration along a third direction which is perpendicular to the main
plane of extension. A Coriolis deflection of the Coriolis element along a
first direction which is parallel to the main plane of extension may be
detected using a detection arrangement. The detection arrangement
includes a Coriolis electrode which is connected to the Coriolis element,
and a corresponding counterelectrode. Both the Coriolis electrode and the
counterelectrode may be excited to a vibration along the third direction.

Claims:

1. A yaw rate sensor, comprising: a substrate, which has a main plane of
extension; a detection arrangement; and a Coriolis element, wherein the
Coriolis element is excitable to a vibration along a third direction,
which is perpendicular to the main plane of extension, wherein a Coriolis
deflection of the Coriolis element along a first direction, which is
parallel to the main plane of extension, is detectable using the
detection arrangement; wherein the detection arrangement includes a
Coriolis electrode, which is connected to the Coriolis element, and a
corresponding counterelectrode, and wherein the Coriolis electrode and
the counterelectrode are excitable to a vibration along the third
direction.

2. The yaw rate sensor of claim 1, wherein the yaw rate sensor has a
drive frame, which is excitable to a vibration along the third direction
and which is coupled to the Coriolis element, and wherein the
counterelectrode is connected to the drive frame, and the
counterelectrode is electrically insulated from the Coriolis element via
an insulating element.

3. The yaw rate sensor of claim 1, wherein the drive frame has a first
partial region and a second partial region, wherein the counterelectrode
is connected to the first partial region, and a further counterelectrode
of the detection arrangement which corresponds to a further Coriolis
electrode of the detection arrangement is connected to the second partial
region, and wherein at least one the following is satisfied: (i) the
first partial region is electrically insulated with respect to the second
partial region, and (ii) the counterelectrode is electrically insulated
with respect to the further counterelectrode.

4. The yaw rate sensor of claim 1, wherein the first partial region has a
first section and a second section, which is electrically insulated from
the first section, wherein the counterelectrode included a first
counterelectrode, which is connected to the first section, and a second
counterelectrode which is connected to the second section, and wherein
the second partial region has a third section and a fourth section which
is electrically insulated from the third section, and wherein the further
counterelectrode includes a third counterelectrode, which is connected to
the third section, and a fourth counterelectrode, which is connected to
the fourth section.

5. The yaw rate sensor of claim 1, wherein the first section and the
third section are at the same electric potential, wherein the second
section and the fourth section are at the same electric potential, and
wherein one of the second section and the fourth section is situated
along the drive frame between the first section and the third section.

6. The yaw rate sensor of claim 1, further comprising: an additional
detection arrangement, wherein a further Coriolis deflection of the
Coriolis element along a second direction, which is perpendicular to the
first direction and the third direction, is detectable using the
additional detection arrangement, wherein the additional detection
arrangement includes a further Coriolis electrode, which is connected to
the Coriolis element, and a corresponding further counterelectrode, and
wherein the further Coriolis electrode and the further counterelectrode
are excitable to a vibration along the third direction.

7. A yaw rate sensor system, comprising: at least two yaw rate sensors,
each of the at least two yaw rate sensors including: a substrate, which
has a main plane of extension, a detection arrangement, and a Coriolis
element, wherein the Coriolis element is excitable to a vibration along a
third direction, which is perpendicular to the main plane of extension,
wherein a Coriolis deflection of the Coriolis element along a first
direction, which is parallel to the main plane of extension, is
detectable using the detection arrangement; wherein the detection
arrangement includes a Coriolis electrode, which is connected to the
Coriolis element, and a corresponding counterelectrode, wherein the
Coriolis electrode and the counterelectrode are excitable to a vibration
along the third direction, and wherein at least one of the following is
satisfied: (i) a first Coriolis element of a first yaw rate sensor is
coupled to a second Coriolis element of a second yaw rate sensor, and
(ii) a first drive frame of the first yaw rate sensor is coupled to a
second drive frame of the second yaw rate sensor.

8. The yaw rate sensor system of claim 7, wherein the coupling is
configured to be one of rigid and spring-elastic.

9. The yaw rate sensor system of claim 7, wherein the first drive frame
of the first yaw rate sensor is coupled to the second drive frame of the
second yaw rate sensor, wherein the first drive frame of the first yaw
rate sensor and the second drive frame of the second yaw rate sensor have
a shared frame element, and wherein the yaw rate sensor system has a
torsional axis which extends along the shared frame element.

10. A method for operating a yaw rate sensor, the method comprising:
exciting a Coriolis element of the yaw rate sensor to a vibration along a
third direction, which is perpendicular to a main plane of extension of a
substrate, wherein the yaw rate sensor includes the substrate, which has
the main plane of extension, a detection arrangement, and the Coriolis
element, wherein the Coriolis element is excitable to a vibration along
the third direction, and wherein the detection arrangement includes a
Coriolis electrode, which is connected to the Coriolis element, and a
corresponding counterelectrode; and detecting the Coriolis deflection of
the Coriolis element along the first direction, which is parallel to the
main plane of extension, using the detection arrangement; wherein the
Coriolis electrode of the detection arrangement and the counterelectrode
of the detection arrangement are excited to a vibration along the third
direction.

Description:

RELATED APPLICATION INFORMATION

[0001] The present application claims priority to and the benefit of
German patent application no. 10 2009 045 420.9, which was filed in
Germany on Oct. 7, 2009, the disclosure of which is incorporated herein
by reference.

FIELD OF THE INVENTION

[0002] The present invention is directed to a yaw rate sensor.

BACKGROUND INFORMATION

[0003] Yaw rate sensors are believed to be generally available. For
example, a yaw rate sensor is discussed in WO 2009/062786 A1, and it has
a substrate and a plurality of movable substructures which are situated
over a surface of the substrate, the movable substructures being coupled
to a shared spring element, and an arrangement being provided to excite
the movable substructures to a coupled vibration in a plane parallel to
the surface of the substrate, and the movable substructures having
Coriolis elements, and an arrangement being provided to detect
deflections of the Coriolis elements caused by a Coriolis force, a first
Coriolis element being provided for detecting a yaw rate about a first
axis, and a second Coriolis element being provided for detecting a yaw
rate about a second axis which is perpendicular to the first axis.

SUMMARY OF THE INVENTION

[0004] The yaw rate sensor according to the exemplary embodiments and/or
exemplary methods of the present invention, the yaw rate sensor system
according to the exemplary embodiments and/or exemplary methods of the
present invention, and the method according to the present invention for
operating a yaw rate sensor according to the other description herein
have the advantage over the related art that a yaw rate about a
rotational axis oriented parallel to the main plane of extension may be
detected via a Coriolis deflection which likewise is oriented essentially
parallel to the main plane of extension and perpendicular to the
rotational axis. Both the Coriolis electrode and the counterelectrode of
the detection arrangement are advantageously excited to a vibration
perpendicular to the main plane of extension, so that no interference
signals are generated by a relative motion between the Coriolis electrode
and the counterelectrode along the third direction. This is achieved in
particular by the counterelectrode not being fixedly anchored to the
substrate, but, rather, being moved together with the Coriolis element
along the third direction. Therefore, a change in capacitance between the
Coriolis electrode and the counterelectrode in particular is not induced
by a motion of the Coriolis element perpendicular to the main plane of
extension; instead, such a change in capacitance is caused primarily by
the yaw rate, so that the yaw rate may be detected with greater precision
via the change in capacitance. The substrate may include a semiconductor
substrate, in particular a silicon substrate.

[0005] Advantageous embodiments and refinements of the exemplary
embodiments and/or exemplary methods of the present invention are further
described herein, as well as the description with reference to the
drawings.

[0006] According to one refinement, it is provided that the yaw rate
sensor has a drive frame which is coupled to the Coriolis element and
which may be excited to a vibration along the third direction, the
counterelectrode being connected to the drive frame, and the
counterelectrode may be electrically insulated from the Coriolis element
via an insulating element. Similarly, the Coriolis element and the
counterelectrode, situated equidistantly from the drive frame, are
advantageously excited to a vibration along the third direction, so that
the Coriolis electrode and the counterelectrode are synchronized to one
another with regard to the vibration along the third direction. The drive
frame may be excited using substrate-mounted flat electrodes which in
particular are situated between the drive frame and the substrate,
perpendicular to the main plane of extension. Alternatively, the flat
electrodes are designed as cover electrodes, so that the drive frame is
situated between the cover electrodes and the substrate, perpendicular to
the main plane of extension. The counterelectrode (also referred to as
the detection counterelectrode) may be electrically insulated from the
Coriolis element, so that the electrical capacitance between the Coriolis
electrode and the counterelectrode may be measured via the difference in
potential between the Coriolis electrode and the counterelectrode. The
insulating element may be positioned in the area of the drive frame or of
the Coriolis element, and in particular includes an insulating material,
for example oxide, nitride, or the like.

[0007] According to another refinement, it is provided that the drive
frame has a first partial region and a second partial region, the
counterelectrode being connected to the first partial region, and a
further counterelectrode of the detection arrangement corresponding to a
further Coriolis electrode of the detection arrangement being connected
to the second partial region, and the first partial region being
electrically insulated with respect to the second partial region, and/or
the counterelectrode being electrically insulated with respect to the
further counterelectrode. A differential evaluation of the Coriolis
deflection is thus advantageously possible. The Coriolis electrode and
the counterelectrode, or the further Coriolis electrode and the further
counterelectrode, are designed in particular as finger electrodes which
intermesh along the first direction, or as capacitor plates which are
oppositely situated along the first direction, so that either the overlap
or the distance between the corresponding electrodes is varied via the
Coriolis deflection.

[0008] According to another refinement, it is provided that the first
partial region has a first section and a second section which is
electrically insulated from the first section, the counterelectrode
including a first counterelectrode which is connected to the first
section and a second counterelectrode which is connected to the second
section, and the second partial region having a third section and a
fourth section which is electrically insulated from the third section,
the further counterelectrode including a third counterelectrode which is
connected to the third section, and a fourth counterelectrode which is
connected to the fourth section. Interference signals resulting from
torsion of the Coriolis element with respect to the drive frame are thus
advantageously prevented.

[0009] According to another refinement, it is provided that the first and
the third sections are at the same electric potential, and the second and
the fourth sections are at the same electric potential, the second or the
fourth section being situated along the drive frame between the first and
the third section, so that a differential evaluation of the Coriolis
deflection may be achieved comparatively easily with little complexity of
contacting.

[0010] According to another refinement, it is provided that a further
Coriolis deflection of the Coriolis element along a second direction
which is perpendicular to the first and to the third direction may be
detected using an additional detection arrangement, the additional
detection arrangement including a further Coriolis electrode connected to
the Coriolis element, and a corresponding further counterelectrode, both
the further Coriolis electrode and the further counterelectrode being
excitable to a vibration along the third direction. The yaw rate sensor
thus advantageously includes a dual-channel sensor which is suitable for
detecting yaw rates about a first rotational axis which is parallel to
the first direction, and also for detecting yaw rates about a second
rotational axis which is parallel to the second direction. It is
advantageous that only a single Coriolis element is required, and the
Coriolis electrode and the counterelectrode in the detection arrangement,
or the further Coriolis electrode and the further counterelectrode in the
additional detection arrangement, vibrate in synchronization with one
another along the third direction, thus avoiding an adverse effect from
interference signals.

[0011] A further subject matter of the exemplary embodiments and/or
exemplary methods of the present invention is a yaw rate sensor system
having a first and a second yaw rate sensor, the Coriolis element of the
first yaw rate sensor being coupled to the Coriolis element of the second
yaw rate sensor, and/or the drive frame of the first yaw rate sensor
being coupled to the drive frame of the second yaw rate sensor. A
differential evaluation of the yaw rate is thus advantageously possible,
and undesired interfering influences due to linear accelerations of the
yaw rate sensor system are minimized.

[0012] According to one refinement, it is provided that the coupling is
designed to be rigid and/or spring-elastic. The Coriolis element of the
first yaw rate sensor and the Coriolis element of the second yaw rate
sensor thus advantageously vibrate along the third direction in phase
opposition. This may be achieved using a rocker structure for a rigid
coupling, or using an elastic coupling of the two drive frames.

[0013] According to another refinement, it is provided that the drive
frame of the first yaw rate sensor and the drive frame of the second yaw
rate sensor have a shared frame element, the yaw rate sensor system
having a torsional axis which extends along the shared frame element. A
comparatively compact implementation of the yaw rate sensor system may
thus be advantageously achieved.

[0014] A further subject matter of the exemplary embodiments and/or
exemplary methods of the present invention is a method for operating a
yaw rate sensor, the Coriolis element being excited to a vibration along
the third direction, and the Coriolis deflection of the Coriolis element
along the first direction being detected using the detection arrangement,
and both the Coriolis electrode of the detection arrangement and the
counterelectrode of the detection arrangement being excited to a
vibration along the third direction. Interfering influences due to a
relative motion of the Coriolis electrode and the counterelectrode along
the third direction are thus advantageously avoided.

[0015] Exemplary embodiments of the present invention are illustrated in
the drawing and explained in greater detail in the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 shows a yaw rate sensor according to a first specific
embodiment of the present invention.

[0017] FIG. 2 shows a yaw rate sensor according to a second specific
embodiment of the present invention.

[0018] FIG. 3 shows a yaw rate sensor according to a third specific
embodiment of the present invention.

[0019] FIG. 4 shows a yaw rate sensor according to a fourth specific
embodiment of the present invention.

[0020] FIG. 5 shows a yaw rate sensor system according to a first specific
embodiment of the present invention.

[0021] FIG. 6 shows a yaw rate sensor system according to a second
specific embodiment of the present invention.

[0022] FIG. 7 shows a yaw rate sensor according to a fifth specific
embodiment of the present invention.

[0023] FIGS. 8a, 8b, 8c, 8d, 8e, 8f, 8g, and 8h show a partial region of a
yaw rate sensor according to a sixth specific embodiment of the present
invention.

DETAILED DESCRIPTION

[0024] Identical parts are always provided with the same reference
numerals in the various figures, and therefore are generally designated
or mentioned only once.

[0025] FIG. 1 illustrates a schematic top view of a yaw rate sensor 1
according to a first specific embodiment of the present invention, yaw
rate sensor 1 having a substrate 2 and a drive frame 5 which is coupled
to substrate 2 via substrate springs 20. Substrate springs 20 are
designed to be soft along a third direction Z which is perpendicular to a
main plane of extension 100 of substrate 2, while the substrate springs
are designed to be hard with respect to first and second directions X, Y,
which are each perpendicular to third direction Z. First and second
directions X, Y are mutually perpendicular. Drive frame 5 is fixed by
substrate springs 20 with respect to a motion parallel to main plane of
extension 100, and substrate springs 20 permit a motion of drive frame 5
perpendicular to main plane of extension 100. Drive frame 5 is connected
to a Coriolis element 3 via frame springs 57, frame springs 57 being
rigid with respect to third direction Z and being elastic with respect to
first direction X, and insulating elements 6 being situated between frame
springs 57 and drive frame 5 and being provided for electrically
insulating Coriolis element 3 from drive frame 5. Drive frame 5 is
excited to a vibration along third direction Z with the aid of drive
elements (not illustrated), Coriolis element 3 likewise being excited to
a vibration along the third direction via frame springs 57. Drive frame 5
is subdivided into a first partial region 50 and a second partial region
51 which is mirror-symmetrical with respect to first partial region 50,
first and second partial regions 50, 51 being electrically insulated from
one another via further insulating elements 6'. First partial region 50
has counterelectrodes 41, designed as finger structures, which are
provided for engaging with corresponding Coriolis electrodes 40 of
Coriolis elements 3, while second partial region 51 has further
counterelectrodes 43, designed as finger structures, which are provided
for engaging with corresponding further Coriolis electrodes 42 of
Coriolis element 3. A yaw rate about a rotational axis which is parallel
to second direction Y generates a Coriolis force which causes a Coriolis
deflection 80 of Coriolis element 3 along first direction X. This
Coriolis deflection 80 changes the overlap between Coriolis electrode 40
and counterelectrodes 41, and the overlap between further Coriolis
electrodes 42 and further counterelectrodes 43, each being measurable as
a change in the electrical capacitance. Coriolis element 3 is optionally
anchored to substrate 2 via further substrate springs 30, further
substrate springs 30 are designed to be soft along first and third
directions X, Z and being designed to be hard along second direction Y.
For illustrated yaw rate sensor 1, Coriolis electrodes 40 and further
Coriolis electrodes 42, as well as counterelectrodes 41 and further
counterelectrodes 43, advantageously vibrate along third direction Z.
Frame springs 57 and/or substrate springs 20 are alternatively designed
as U-springs.

[0026] FIG. 2 illustrates a schematic top view of a yaw rate sensor 1
according to a second specific embodiment of the present invention; in
contrast to the first specific embodiment illustrated in FIG. 1, drive
frame 5 is situated within Coriolis element 3, while Coriolis element 3
is designed as a framelike structure. Coriolis element 3 in turn is
fastened to substrate 2 via further substrate springs 30, and is coupled
to drive frame 5 via frame springs 57. Furthermore, drive frame 5 in turn
is fastened to substrate 2 via substrate springs 20. In this case drive
frame 5 is not subdivided into first and second partial regions 50, 51,
and instead Coriolis element 3 is subdivided into two partial elements
31, 32 which are electrically insulated from one another via further
insulating elements 6', so that Coriolis electrode 40 is electrically
insulated from further Coriolis electrode 42.

[0027] FIG. 3 illustrates a schematic top view of a yaw rate sensor 1
according to a third specific embodiment of the present invention, the
third specific embodiment essentially having the structure of the first
specific embodiment, and, similarly as in the second specific embodiment,
the drive frame is not subdivided into first and second partial regions
50, 51, but, rather, the Coriolis element is subdivided into two partial
elements 31, 32.

[0028] FIG. 4 illustrates a schematic top view of a yaw rate sensor 1
according to a fourth specific embodiment of the present invention, the
fourth specific embodiment being essentially the same as the first
specific embodiment illustrated in FIG. 1, and detection arrangement 4
being designed not as intermeshing finger structures, but as plates of a
plate capacitor. The change in the electrical capacitance for detecting
Coriolis deflection 80 is therefore no longer caused by a change in the
degree of overlap of the finger structures, but, rather, by a change in
distance between the plates. In addition, first partial region 50 is
separated into a first section 52 and a second section 53 which is
insulated therefrom, and second partial region 51 is separated into a
third section 54 and a fourth section 55 which is insulated therefrom.
Counterelectrodes 41 therefore include a first counterelectrode 44 which
is connected to first section 52, and a second counterelectrode 45 which
is connected to second section 53, further counterelectrode 43 including
a third counterelectrode 46 which is connected to third section 54, and a
fourth counterelectrode 47 which is connected to fourth section 55.
Insulating elements 6 are designed in such a way that they electrically
insulate first and second sections 52, 53 and third and fourth sections
54, 55, respectively, from one another. First and fourth sections 52, 55
and second and third sections 53, 54 are optionally at the same electric
potential.

[0029] FIG. 5 illustrates a schematic top view of a yaw rate sensor system
11 according to a first specific embodiment of the present invention, yaw
rate sensor system 11 having two yaw rate sensors 1, 1', i.e., a first
and a second yaw rate sensor 1, 1' according to the fourth specific
embodiment illustrated in FIG. 4, which are elastically coupled to one
another via a coupling element 90. Vibration 91 of drive frame 5 or of
Coriolis element 3 of first yaw rate sensor 1 along third direction Z is
antiparallel and in phase opposition to vibration 91 of drive frame 5',
or of Coriolis element 3' of second yaw rate sensor 1' along third
direction Z, so that Coriolis deflection 80' of second yaw rate sensor 1'
is also antiparallel and in phase opposition to Coriolis deflection 80 of
first yaw rate sensor 1, and a differential measurement of the yaw rate
is therefore made possible without interfering influences of a linear
acceleration of yaw rate sensor system 11.

[0030] FIG. 6 illustrates a schematic top view of a yaw rate sensor system
11 according to a second specific embodiment of the present invention,
the second specific embodiment essentially corresponding to the first
specific embodiment illustrated in FIG. 5, first and second yaw rate
sensors 1, 1' being fixedly coupled to one another and having a shared
frame element 56. In this case, first and second yaw rate sensors 1, 1'
undergo a mutual rotary vibration 92 about a torsional axis 93 which
extends along shared frame element 56.

[0031] FIG. 7 illustrates a schematic top view of a yaw rate sensor 1
according to a fifth specific embodiment of the present invention, the
fifth specific embodiment being essentially the same as the fourth
specific embodiment illustrated in FIG. 4, yaw rate sensor 1 having an
additional detection arrangement 7 which is used for detecting a further
Coriolis deflection 81 along second direction Y which is caused by a yaw
rate having a rotational axis parallel to first direction X. Additional
detection arrangement 7 includes two Coriolis electrodes 70 which are
connected to Coriolis element 3 and which cooperate with further
counterelectrodes 71 of drive frame 5.

[0032] FIGS. 8a through 8h illustrate schematic views of partial regions
of yaw rate sensors 1 according to a sixth specific embodiment of the
present invention, partial regions having an insulation arrangement 6
which, for example, provide electrical insulation of first partial region
50 of drive frame 5 from second partial region 51 of drive frame 5.
Insulation arrangement 6, i.e., the lateral layer, may include an
insulating material 62, for example trench pits filled with oxide or
amorphous SiGe, insulating material 62 may be situated below, above, or
on both sides of the functional layer. In FIGS. 8e through 8h, insulation
arrangement 6 also includes a conductive layer 61, which for example is
situated below, above, or on both sides of the functional plane,
insulating material 62 may be electrically insulating conductive layer 61
from the functional plane. The functional layer includes, for example, a
first and a second partial region 50, 51 of drive frame 5. In FIG. 8h,
conductive layer 61 is partially embedded in insulating material 62. The
conductive layer may be embedded in an oxide, and a printed conductor
plane situated therebelow is used as shielding from the oxide etching at
this mechanical connection. The sacrificial layer etching is carried out
in a time-controlled manner in such a way that the oxide remains to a
sufficient degree on the mechanical connecting element.